The present invention relates to air bearing sliders for disc drives, and more particularly, to air bearing sliders having an air bearing surface which is removed from a corner of the slider body.
Air bearing sliders have been extensively used in magnetic disc drives to appropriately position a transducer above a rotating magnetic disc. The rotation of the disc at high speed generates a "wind" of air immediately adjacent the flat surface of the disc. A disc opposing face the air bearing slider interacts with the wind to bias the slider away from the disc and against a load beam, causing the slider to "fly" a small distance above the disc. Each slider is typically mounted on a gimble or load beam assembly which biases the slider toward the rotating disc, providing a spring force opposite to the bearing force of the wind incident on the disc opposing face of the slider.
When a disc drive is subjected to a mechanical shock of sufficient amplitude, the slider may overcome the biasing force of the load beam and lift off from the disc. Damage to the disc may occur when the slider returns to the disc and impacts the disc under the biasing force of the load beam. The damage to the disc can result in lost or inaccurate data, or in a fatal disc "crash" rendering the disc drive inoperable.
The contour of the disc opposing face of an air bearing slider has a significant effect on the flying characteristics of the air bearing slider, and various contours have been proposed and used for air bearing sliders. Examples of two of these are included in U.S. Pat. No. 5,062,017 to Strom et al. and U.S. Pat. No. 5,343,343 to Chapin, assigned to the assignee of the present invention and both incorporated herein by reference.
The disc opposing face of most air bearing sliders includes a defined "air bearing surface" which is a flat surface closest to the disc or extending furthest from the body of the slider. The air bearing surface is generally planar, but may have a slight crown. A tapered or stepped front edge may be included at the leading edge of the air bearing surface. One or more cavities is defined in the disc opposing face and having a generally constant depth from the air bearing surface. In particular, many sliders include an air bearing surface made up of two or more "rails" or "skis" running longitudinally along the disc opposing face. A large central cavity is commonly defined between two air bearing rails of the slider. In "negative pressure" air bearing sliders (or NPABs), a cross bar or other structure toward the leading edge of the slider is used to provide a negative pressure region in the central cavity.
In some air bearing sliders, such as that shown in Strom et al., the air bearing surface may extend the full length of the slider body and may include leading and trailing corners of the slider body. In other air bearing sliders, such as that shown in Chapin, a longitudinal edge step may be used such that the air bearing surfaces are removed inward from corners of the slider body.
The fabricating processes used to manufacture air bearing sliders commonly includes photolithographic material removal processes. In photolithographic removal, a protective coating may be applied to a portion of the disc opposing face of the slider body, and a thin layer of material not protected by the coating may be removed by a chemical or physical process. The chemical or physical process removes material over the exposed surfaces at a substantially uniform rate. The depth of the removed material is determined by the length of application time for the chemical or physical material removal process. Other processing steps include mechanical removal of material such as through lapping or polishing surfaces.
It is common to simultaneously manufacture a number of sliders arranged side by side along a "bar". After each of the air bearing surfaces has been defined and commonly machined on the bar to the extent possible, the bar is diced into individual air bearing sliders. Because processing steps require approximately equal expense regardless of whether performed on multiple aligned sliders at once or on a single slider, "bar level processing", i.e., the simultaneous processing of multiple sliders each part of the bar and prior to dicing, is significantly more efficient than "slider level processing".
In bar level processing, the air bearing surface, the leading edge and the trailing edge can be polished very flat and smooth. The surfaces produced by the machined dice cuts, however, are quite rough with jagged edges compared to the polished edges of the air bearing surface. Because polishing of the side edges of the slider body would require slider level processing, the sides of the slider may be left with the as cut edges and without any lapping, polishing or other finishing operations on the sides of the slider.
The disc drive industry generally desires to manufacture disc drives which are more robust at withstanding shock events. At the same time, the contour of the air bearing surface of sliders is dictated to maximize flying performance, and the processing of sliders should be performed as efficiently as possible to reduce cost. The present invention addresses these concerns, and provides a more robust disc drive without significantly increasing cost or sacrificing slider performance.